Dry friction between hair fibers plays a major role in the collective hair dynamic behavior as it accounts for typical nonsmooth features such as stick-slip instabilities. However, due the challenges posed by the modeling of nonsmooth friction, previous mechanical models for hair either neglect friction or use an approximate smooth friction model, thus losing important visual features. In this ...

The construction of fast and reliable solvers for contact problems with friction is even nowadays a challenging task. It is well known that contact problems with Coulomb friction have the weak form of a quasi-variational inequality [KO88, HHNL88, NJH80]. For small coefficients of friction, a solution can be obtained by means of a fixed point iteration in the boundary stresses [NJH80]. This fixe...

The design of a controller for a flexible system under the influence of friction is presented. A linear programming technique for finding an optimal control of linear flexible systems is extended to frictional systems. A floating oscillator is used in the development, where friction and control input forces are acting on the first mass. The result of the linear programming is a control profile ...

This paper is concerned with residual error estimators for finite element approximations of Coulomb frictional contact problems. A recent uniqueness result by Renard in [72] for the continuous problem allows us to perform an a posteriori error analysis. We propose, study and implement numerically two residual error estimators associated with two finite element discretizations. In both cases the...

The paper deals with a discrete model of a two-dimensional Signorini problem with Coulomb friction and a coefficient of friction F depending on the spatial variable. It is shown that a solution exists for any F and is unique if F is sufficiently small. We also prove that this unique solution is a Lipschitz continuous function of F . Numerical realization is done by the piecewise smooth Newton m...

Depending on the application, friction in mechanical systems can be a desirable or an undesirable thing. In order to optimally utilize or compensate for the frictional effect in the system, characterization of the frictional behavior is a crucial task. Unfortunately, friction force exhibits strong (hysteretic) nonlinear relationship with sliding velocity, displacement and time, which makes the ...

Two experiments were performed to determine the effects of friction and needle geometry during robotic needle insertion into soft tissues. In Experiment I, friction forces along the instrument axis were characterized during needle insertion into bovine liver under CT fluoroscopic imaging. Because the relative velocity of the tissue and needle affect viscous and Coulomb friction, the needle inse...

In this paper, a new approach employing both adaptive and robust methodologies is proposed for stick—slip friction compensation for tracking control of a one degree-of-freedom DC-motor system. It is well known that the major components of friction are Coulomb force, viscous force, exponential force (used to model the downward bend of friction at low velocity) and position-dependent force. Visco...

nt matter & 2007 IAgrE. temseng.2007.02.013 thor. Tel.: +1 217 333 2854; : [email protected] (T.E. Gri This paper describes the development of a device capable of measuring the dynamic friction coefficient of particles accelerated in a tube spinning in a horizontal plane. The dynamic friction coefficient is not the classical Coulomb friction coefficient, but a lumped parameter influenced by the Co...